The invention relates to a cutting apparatus for webs wound onto core tubes on a pair of support rolls driven in rotation.
In the shaftless winding of webs of paper, fabrics or plastics into rolls, a core tube is inserted into the wedge between two rotatable support rolls which are spaced from each other and whose axes are parallel to each other, and at least one of which is driven. The head end of the web is fastened to the circumference of the core tube, which is then caused to rotate by the pair of support rolls, the web thus being wound onto the core tube. The completely wound web roll is lifted off the pair of support rolls or pushed out of the way. Before or during this operation, the web is cut. The new web head end so formed is attached to a new core tube.
The web is difficult to cut because of the narrow gap between the support rolls and the resultant poor accessibility. Up to now this operation has been performed either before the ejection of the wound roll, by cutting its top winding by means of a wedge as with a letter opener, or, in the case of hard-to-tear materials, by first ejecting the roll and then cutting the stretched web in proximity to the first support roll. Since at the start of the winding operation the wedge between the support rolls is largely filled by the core tube, there is no room for a stationary cutting blade. Now if the efficiency of the winding machine is to be improved, it must be sought to effect the core-tube change as economically as possible, which means that the operations involved in said change, including the cutting of the web, must entail practically no loss of time and no waste of material.